#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>

int main()
{
	int i, k;
	k = 1;
	double sum = 0;
	for (i = 1; i <= 100; i++)
	{
		sum += 1.0 / i * k;
		k *= -1;
	}
	printf("%f", sum);
	return 0;
}